All the fuel tanks have been rigorously tested and cleaned following a regrettable error, JET has said.
The petrol station in Desborough Park Road, High Wycombe, informed motorists earlier this week they will be reimbursed "accordingly."
It comes after several motorists were left with damaged cars after filling up with contaminated fuel in January.
A spokesman said: "We regret this situation and would like to apologise again to all affected customers. We have taken immediate action to rectify this.
"All tanks have been thoroughly tested, cleaned and re-lined. We have taken this opportunity to introduce a new grade of fuel - Jet Super Diesel when we changed the tanks.
"All affected customers have been given details of our insurers and will be reimbursed accordingly.
"We would like to reiterate that we have taken all necessary action to ensure this does not happen again and are committed to serving our community."
Several Jet customers have got in touch with the Free Press complaining they are yet to be reimbursed.
Danraj Gill claims he spent more than £1,000 repairing his car after it was damaged from contaminated Jet fuel.
He said: "I am really concerned I will not be reimbursed.
"I have spent over £1k rectifying my car and I am currently out of pocket with no hope of getting it back. I have messaged the owner again this morning but no luck."
Marian Coman brought the issue to light when he filled up his car on Saturday, January 6, to buy diesel.
He filled up the car with 14 litres of diesel when 20 minutes later, an error message popped up on the car dashboard reading: "Water in fuel - Contact Service".
Since then, he has had "no luck" receiving a response from the company or payment for the damage to his car.
He said: "I've received no information from them about their insurers plus the owner avoiding to answer me. I don't feel good at all because I thought that they will sort the matter quicker due to the fact that they've admitted the mistake. I was left out of pocket for some time.
"I have nothing against them as a business, because I've used them in the past as well and had no issues filling up there but now is just the fact that they are not responding to me."
Rosan Lewis said: "I emailed Jet on the 25th of January with the invoice for my Jeep and still have not heard anything back from them.
"I’ve been calling the manager and no one is answering, I went into the shop several times and left my contact details and they haven’t reached out. I would like to know what is really going on."
Jet has been approached for further update.
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